On Jan 8, 2008, at 12:50, Don Collie wrote: > I`d just hang an AC millivoltmeter[or microvoltmeter] across the > regulator`s > output. > I use my H/P 400H, which will give readings down to about 50uV. If > your > regulator produces less noise than this [say a 723, with > 2uV], then you`ll need a more sensitive meter.
Electronic voltmeters or microvoltmeters have a noise bandwidth which is larger than the bandwidth on the front panel. The front panel bandwidth is related to accuracy and is not the -3dB bandwidth. The noise bandwidth is nearly always range setting dependent and can vary very much. I have seen a factor of four in noise bandwidth between adjacent range settings. The only way to have a good indication on noise is in a known and constant bandwidth. The noise bandwidth of a filter is not the same as the 3dB bandwidth and dependent of the filter order and shape. It is always more. Henk _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
